We have one old apple tree on our property and 3 years ago we planted several new apple trees. This year I have noticed black looking bark on the old apple tree (unknown variety) and also on the honeycrisp and freedom apple trees. I looked online and am wondering if this is black rot, or possibly fire blight? Should we consider removing the old tree? Also for the young trees, is there any treatment? I had read to remove affected limbs, but the growth is on the main trunk, so we'd have to basically cut the whole tree. Ant advice would be much appreciated. Thanks.